Addressing Adverse Drug Reactions

Addressing Adverse Drug Reactions

A new CIHI report found that, in 2010–2011, about 27,000 older Canadians became hospital inpatients because of adverse reactions to their drugs. Put another way, that is 1 in 200 people older than 65—a proportion far removed from the national average of about 1 in 1,000.

“This is a common problem,” said Dr. David Hogan of the University of Calgary.

This isn’t about fear-mongering, either, just facts that need to be considered.

“Canadians are often hospitalized because of issues with their medications,” Dr. Hogan continued. “Many beneficial medications have a narrow therapeutic window and you have to be careful. There is, unfortunately, some inherent risk.”

Dr. Hogan, who is the university’s chair of geriatric medicine, said we must settle somewhere in the gap between being cognizant of these risks and overreacting to them. These are, after all, medications that people need to heal.

At the heart of the issue are aging Canadians. More likely to have a fistful of prescriptions to manage several conditions, they face more complex prescribing patterns. Dr. Hogan said an older body is simply more vulnerable, unable to tolerate a drug-induced stress that it could have decades earlier. Toss in declining renal function and a changing ability to metabolize drugs, and someone may face an adverse response to an otherwise appropriate prescription.

Most Common Culprits

Topping the list of medications most linked to hospitalizations due to adverse drug reactions (ADRs) were blood thinners. These drugs, including the widely prescribed warfarin, were linked to 12.6% of ADR hospitalizations among seniors. Following closely behind were chemotherapy drugs at 12.1%, then opioids at 7.4%.

“Blood thinners are beneficial but have that narrow therapeutic window,” Dr. Hogan said. “They are often altered by other medications or a diet change. They are finicky. They require careful monitoring. The challenges in prescribing to an older adult often come down to these situations.”

Staying Safe

Dr. Hogan believes drug safety relies on a partnership between patient, prescriber and pharmacist. It is difficult for patients to stay vigilant, because it is often hard to distinguish between an adverse effect and a medical problem one knows is already present.

“Older individuals must be armed with knowledge. They must know about the more common and more serious side effects when they are prescribed a medication, and be given clear instructions about what they should do in the event of problems.”

Dr. Hogan also said this cognizance extends into the over-the-counter realm. Supplements, herbal remedies and medicines can interfere with a prescribed drug’s path in the body. They can disrupt its storage, distribution and how it is metabolized. “Adding any medication to a drug regimen does complicate the regimen.”

He said it is important that pharmacists and physicians keep this in mind when they are advising patients about medications. And for patients, he suggests one good, clean rule. “If ever unsure, ask.” Plus, he recommends a tip sheet he co-authored on avoiding ADRs.

Of the CIHI report, Dr. Hogan said it “brings the whole issue home here to Canada.

“It will hopefully lead to improved prescribing and appropriate consuming of medications.”